Means for changing wave lengths



' 1,639,696 Aug. 23, 1927. G'HILL ET AL umms FOR CHANGING WAVE LENGTHSFiled May 5, 1915 3 Sheets-Sheet 1 INVENTORS vi X46151 i M' ATTORNEY\NITNESSES Aug.' 23, 1927.

G. HILL ET AL MEANS FOR CHANGING WAVE LENGTHS Filed May 5; 1915 3Sheets-Sheet 3 WITNESSES \MI' I 6M 7 BY m 6 6w I A-rroRNEY Patented Aug.23, 1921.

UNITED STATES PAFTSENT OFFICE.

GUY HILL, 0! BROOnYN, NEW YORK, AND GEORGE H. CLARK, OF WASHINGTON, DIS-TBICT O1 COLUMBIA, ASSIGNORS, BY MESNE ASSIGNMENTS, TO RADIO CORPORA-TION OF AMERICA, A CORPORATION OF DELAWARE.

HANS FOB CHANGING WAVE LENGTHS.

Application fled Kay 8,

Our invention relates to telegraphy, telephony, or like systems in whichthe energy employed is in the electro-radiant form for space systems orin the form of high frequency oscillations for conductive systems.

It is an object of our invention to provide, either at the transmittingor receiving station, or both, improved apparatus whereby settings fordifferent wave lengths or freuencies may be made by a single operat1onof switching mechanism which shall at the same time ensure proper ordesired coupling between inductively related oscillation circuits.Further objects of our invention are to provide means for simultaneouslyswitching in or out parts of a loading inductance or parts of a capacityin the closed oscillation circuit, or both. And a still further objectis to provide improved structure of an inductance, as a loadinginductance, together with means for permitting adjustment of a sectionwhile the adjusting means for the other sections are locked.

To these ends we have devised the system and apparatus hereinafterdescribed and constituting an embodiment of our invention.

For an illustration of some of the many forms our invention may takereference is to be had to the accompanying drawings, in which: 1 a

Fig. 1 is a diagrammatic view illustrating a typical transmittingapparatus to which our invention may be applied.

Fig. 2 is a diagrammatic view illustrating electrical connect-ion andco-operating switching mechanism for carrying out our invention.

Fig. 3 is a longitudinal section, some parts in elevation, showing oneform of apparatus for carrying out our invention.

Fig. 4. is a diagrammatic view, partially structural, illustrating aswitching panel controlling the primary of a transmitting apparatus.

Fig. 5 is a plan view of a moving switching clement co-operating withthe structureillustrated in Fig. 4.

Fig. 6 is a diagrammatic view, partially structural, illustratingswitching panel for controlling the secondary and antenna load inginductance.

Fig. 7 is a transverse sectional view, some eluded for purposes ofconvenience.

1815. Serial No. 25,354.

parts in elevation, taken on the line X-X of Fig. 3.

Fig. 8 is a diagrammatic view similar to Fig. 2 when used in receivingapparatus.

Fig. 1 shows a typical transmittin paratus to which reference is made fexplanation of our invention. 'Re'ferring to this figure, G is analternating current generator or other suitable source of currentconnected in circuit with the primary 1) of a step-up transformer, theprimary circuit being controlled by the usual transmitting key is. Thehigh tension secondary s of the step-up transformer has its terminalsconnected to either side of the ap- Ol' an spark gap g which may be ofthe simple type indicated or may of the quenched gap type, or any othersuitable type. The gap 9 is in circuit with the condenser or capacity Kand the variable portions of the primary P of the oscillationtransformer the circuit PK being here shown as a closed oscillationcircuit. The open or antenna circuit comprises a variable portion of thesecondary S of the oscillation transformer, a variable portion of theloading inductance L, beyond the inductive influence of the primary P,the antenna or aerial conductor A,

and the earth connection E, a radiationmeter M, such as a hot wireammeter, being in- When it is desired to transmit ener of a certainfrequency or wave length, t e variable or sliding contact in the primarycircuit is moved to' such point on the primary P, as for example thepoint 1, which will ensure the primary circuit producing oscillations ofthe desired frequency, corresponding with wave length No. 1. Thissetting may be determined by a wave meter, by calculation, or otherwiseThe open or antenna q circuit is then attuned to this same frequency orwave length, when the coupling between' P and S is loose; by adjustingthe variable contacts on S and on L until the meter M gives a maximumreading. Then by making the coupling between P and S closer and ofmitting energy having wave length No. 1 the rider orcontact sliding onthe loading inductance L will have to be moved to some new positionuntil the wave meter indicates but a single maximum in the resonancesuch character as is to be employed in trans curve, and the adjustmentis further varied until with this single maximum in the resonance curvethe meter M; indicates a maximum reading for that particular coupling.

And in this connection the point 1 in the rimary P may have to be variedslightly rom its first setting. However, by these well-known methods thesetting of the inductance L, of secondary S and of rimary P aredetermined for the wave lengt No. 1. Similarly for another wavelength,sa No. 2, the settings will be at the points indicated by 2; thesettings for a third wave length by 3, and for the 4th wave length by 4.

In all cases the necessary or desired inductance in the antenna or opencircuit for any given wave length can be so proportioned between thesecondary S and the loading inductance L that the same mechanicalcoupling, that is, same physical or mechanical distance or relationbetween the primary P and secondary S can be obtained for all wavelengths. In making this adjustment of the relative amounts of inductancein S and L for any wave length, if the cou ling is too close, the numberof turns in S is reduced and the number of turns in L is increased, andconversely if the coupling is too loose, the'number of turns in L isreduced, and the number of turns in S is increased.

By our invention we provide switching mechanism, a single movement ofwhich will transfer the movable contacts on P, S and L to the properpoints for transmission of these various wave lengths while maintainingthe desired or proper coupling between the primary P and the secondaryS, this coupling being generally such as will I cause a transmission ofmaximum ener contacts P P P and P adapted to be engaged by the switcharm P".

Similarly the four points '1, 2, 3vand 4 on the secondary S areconnected respectively with the four switch contacts S S, S and S,

I with which the movable switch arm S is adapted to engage.

And similarly the four points 1, 2, 3 and 4 on the inductance L areconnected with the four switch contacts L L L and L with which theswitch arm L' is. adapted to engage. Inductance L is here shown asdivided into two parts, though a greater number may be employed ifdeneaaooe sired, in order that when one part of the-'inductance is notin use it may be cut out of circuit (501 short circuited as hereinafterdescribe to prevent ener nections are made .from the jacent ends of thetwo inductance portions by conductors a and b with the switch contacts aand d which are adapted to be bridged, when both parts of the inductanceare to be used, by the switch contact 6. The antenna A is connected withthe switch arm L'. And the switch arm S connects to the earth B throughthe radiation meter M and, if desired, an additional variable inductanceL, which may be set at once for all wave lengths of a group, may beemployed.

And in the primary circuit an additional inductance L may be employed ifrequired or desired.

The switch arms P', S', L and e are mechanically connected together, asby member orshaft I, which may be provided with a hand wheel or otheroperating device 71..

In this figure are shown two condensers or bank of condensers K, K whichmay be connected. in parallel or in series with each other under variouscircumstances. Switching mechanism for changing these condenserconnections comprises stationary switch contacts z', j, m, n, 0, and theblank 9. The two movable contacts 1 and t are mechanically connectedtogether but insulated from each other and mechanically connected withthe operating mechanism forthe switches previously described, thisconnection causing the contacts r and t to be in position shown, andthereby connect the condensers K, K in parallel with each other, for thethree right hand positions of the switch P", but when the switch Pengages with contact P, the contacts t, 1' are shifted toward the left,1" remaining in contact with and engaging the blank 9, while If remainsin contact with n and connects the same to o, in which case thecondensers K, K are in series with each other in the primary circuit,the switch P' being connected with the contact m. The object of this isto have less capacity in circuit for the shorter wave length or wavelengths so that the corresponding co-operating inductance of the primarycircuit will be a substantial part of the primary P. And in reversemovement ,of the switch arm P, the switch contacts t and r are restoredto the position shown and occupy such osition for all positions of theswitch arm when 'en aging contacts P, P and P.

ith the arts in the position illustrated in Fig. 2 t e connections aresuch as to transmit wave length No. 3, the amount of inductance L, thecoupling between P and S, and-the number of turns or length of P in theprimary circuit being proper for this wave length. When shifting to anyof the consumption by such 1 le portion. Fort is urpose confillcontactsand d.

In Fig. 3 the primary P and the secondary S of the oscillationtransformer are both shown in the form of spirals carried uponinsulating supports 11 and 12 carried by a suitable frame B, thesecondary S being movable to and away from the primary P, by

- sliding in the frame B, for variation of coupling when desired. On theleft end of the frame B is the primary circuit control panel and on theright end the panel for controlling the connections to the secondary Sas 1 well as the connections to the antenna loading inductance L whichlatter is shown divided into four parts, L, L, L and L, all in the formof flat spirals, supported respectively on the insulatin frames ormembers'13, 14, 15, and 16 carried in a frame C.

' Secured to the shaft f of Fig. 3 is the member D, of insulatingmaterial, the same' being shown in plan in Fig. 5, for co-operation withthe contacts shown in Fig. 4. The

- member D carries the fixed contact or switch point P adapted to engagethe contacts P P, P and P carried on the frame mem ber B as indicated inFigs. 3 and 4. Beneath the contacts P P and 1 are the are shapedcontacts u, v, and w, the latter being connected also to the short areshaped contact a: as:ociated with switch contact P The member D hasthree rows of holes, the holes of each row beingon a radial line, theseholes adapted to receive the plug contacts 10 p and 72 carried by'theremovable insulating plate or, member F, the plug 12 being in permanentelectrical connection with the switch point P in all positions and theplugs and 19 being electrically connected with each other. It will beunderstood that the member -F carrying the aforementioned plugs may beinserted in the member D in the position shown in Fig. 5 or in either ofthe positions to the right or left thereof. In all positions the plugsextend through the holes of the member D, p cooperating with the areshaped contacts and w, the plug p with the are '1), and the plug p withthe arc w. With the plugs in the position indicated in Fig. 5, and withthe switch contact P in engagement with 1, P or P the condensers K, Kwill be found to be connected in parallel with each other. 'With theparts in the same position and the switch point P en agement withcontactP the condensers K, will be in series with each other. With the plu scarried by member F dis osed'to the rig t of the. ition illustrate inFig. 5, that 1s,in the rig t hand row of holes, the followin condensercon nections'will result: with on P or P the fcondensers K, K will be inseries witl each other in the oscillation or closed circuit. With P on Por P the condensers will be in parallel'with each other and in series inthe oscillation or closed circuit. With the plugs carried b member Fmoved to the left hand row of oles in member 'D the condensers K, K,will be connected in parallel with each other when P is on P, P, P or P.And with the switch point P on contact P whatever the nature ofconnection of condensers K, K, either series or parallel, a condenser K,for use on very short wave lengths, may be thrown into series with themby opening the switch y which when closed short circuits the condenser Kthe switch 3 may be manually operated through shaft f by suitablemechanical connection therewith.

The switching mechanism above described and involving the members F andD permits a standard apparatus involving them to be used under variousconditions or characteristicsof primary circuits as regards primarycircult capacity and inductance of the leads or connections. With agiven installation it mlght be necessary or advantageous to have thecondensers in series for certain of the wave lengths, as No. 1 and No.2, and in parallel with each other for other wave lengths, as No. 3 andNo. 4, while with another installation it might be necessary oradvisable to have the condensers in parallel for all four wave lengths.

At the other end of the frame B, Fig. 3, is the panel arrangement shownin 6. Here the switches S and L of Fig. 2 are in effect a singleconducting member rotatcd by but insulated from the shaft 7''. There isa permanent connection .2 from the switch contact L to the rotatin armL, S whereby those parts of the inductance L which are not co-operatingfor each setting are short circuited. Thus when L is on contact 'L thesection L of the loading inductance is short circuited. When on L, asshown, sections D and L are short circuited. And when on L, sections L",L and L are short circuited. This short circuiting arrangement is thealternative of the open circuit arrangement by switch e of Fig. 2.

It will be noted from Figs. 2 and 6 that the connections to theinductance L are shown as variable in their position. With any givenantenna or complete outfit it is found that from time to time there is avariation or change in the electromagnetic or electrostatic constants ofthe apparatus embraces the edge of the inductance conductor and isrotated by and movable ra dially on the arfn a to adjust w1th nicety theamount of inductance L in the open cir uit. These contacts 0 are notmoved simultaneously. Each is movable only when the switching apparatusis set for the particular wave length for which said contact 0 comesinto operation and is effective in sli htly varying the amount ofinductance which is in use for the wave length in question. For thispurpose the arms a are loosely pivoted upon the shaft f and each of thearms a carries teeth or projec tions a adapted to engage incorresponding depressions in the bushings a which rotate with the shaftf but may move longitudinally with respect to the shaft 7 in oppositionto the springs a, one end of each being connected to its bushing a, andits other end to a pin a carried by the shaft 7. Back of each member ais a wedge-shaped member 6 having its point disposed between the membera and a collar b secured upon the shaft f Each member 6 is at the lowerend of a rod 6 whose upper end engages a cam. These cams are indicatedat c, 0 c and a and are all rigidly secured upon the shaft 7" connectedin definite me chanical relation with the shaft 7, as by sprocket chain0 passing over sprocket wheels on the shafts f and 7.

When the operator moves the handle it for setting the switches P, L, andS he will move it, for example, to such position that switch contacts P,L and S are brought into circuit. In so rotating the "shaft f, the shaft7' will be rotated to such osition that the cam 0 will depress the rod 5to cause the wedge b to force the clutch member a into engagement withthe arm a carrying the contact 0 which co-operates with the inductancesection L. The result is that by turning the hand wheel 71. secured toshaft 7 only that arm a co-operating with inductance L may be rotated toadjust with nicety the position of the contact 0 of that inductancesection; all the other arms a are incapable of movement at this time.And so for each wave length transmitted, or for each position of theshaft f, one or another of the cams o crates its co-acting rod 6 to makepossib e fine adjustment of one of the inductance sections, and it isalways that one which is effective for the particular Wave lengthtransmitted.

The inductance sections L, L,'etc. are preferably within inductiveinfluence upon each other, in which case a relatively small eradjustment of contact 0 upon its associated section is necessary toeffect a given variation of inductance than in the case where thosesections are beyond inductive influence by each other.

While the apparatus thus far described has been transmitting apparatusit will be understood that the same functions may be procured forreceiving apparatus.

Thus in Fig. 8 Fig. 2 has been reproduced but in place of the apparatusshown in the receiving on different wave lengths the op erator needmerely turn the hand wheel h to any of the positions, and then byvarying V and K maximum response will be ob tained by tuning.

While with our apparatus hereinbefore described the change from one wavelength or frequency to another is accomplished by a single movement. asby a single actuation of the hand wheel h for a given position of thesecondary S with respect to the primary P, or a given separation betweenthem. our invention comprehends also the accomplishment of the sameresult for different relative positions of or separations between thesecondary S and the primary P, both when such separation is changed bymanually shifting one or the other and when suchseparatlon is changed orvaried by mechanical means.

The shaft f need not be rotated or actuated manually but may be actuatedby a suitable motive device electrically or otherwise controlled from adistance to cause the shaft 7 to partake of the proper degrees ofrotation for shifting the mechanism to the proper positlons for thevarious wave lengths or frequencles.

While we have herein shown and described the inductance L in the open orantenna circuit as divided into sections L, L, etc, with means foradjusting any one of these sections while the others are locked againstsuch adjustment, it is to be understood that we may use in the other orassociated circuit, as the primary circuit, an inductance which may besimilarly varied, and while any one section is variable, the others arelocked against variation. In other words the inductance L of Fig. 2could be so arranged in sections each variableor adjustable while theothersare locked against variation or ad- 'ustment, the mechanism forthe u ose ing like that in the lower half Fig. 3

and coupled to the shaft 7'.

1 What we claim is: v

I 1. The combination with an antenna, of

rimary and secondary windings of an oscilation transformer, switches andconnections therefrom to said primary and secondary windings formaintaining predetermined coupliii s between them for each of aplurality of ifli'erent oscillation frequencies,a plurality ofcapacities in circuit with one of said windings, and switches foraltering the relations of said capacities to the circuit in- 'cludingthem, and means common to all of said switches for actuating them inunison.

2. The combination with an antenna, of

rimary and secondary windings of an oscillation transformer, aninductance in circuit with one of them, switches and connections withsaid primary, secondary and said induc tance for maintainingpredetermined cou plings between said "primary and secondary windings,and procuring the requisite amount of inductance for each of a luralityof oscillation frequencies, said in uctance bein divided'into' sections,a switch for preventing dissipation of energy in a section of saidinductance which is not co.-operating with said primary and secondarywindings, and means common to all .of said switches for actuating themin unison.

3. The combination with an antenna, of rimary and secondary windings ofan osciliiltion transformer, an inductance in circuit with one of them,switches and connections with said primary, secondary and saidinductance for maintaining predetermined couplings between said primaryand secondary windings, and procuring the requisite amount of inductancefor each of a plurality of oscillation frequencies, said inductancebeing divided into sections, a switch for preventing dissipation ofenergy in a section of said in-' ductance which is'not co-operating withsaid primary and secondary windings, a plurality of capacities incircuit with one of said windings, and a switchjfor altering therelations of said capacities with respect to the circuit in which theyare included, and

means common to all of said switches for actuating them in unison.

4. The combination with an antenna, of a primary and secondary of. .anoscillation transformer, additional inductance switches and connectionswith said primary, secondary and said inductance for maintaining apredetermined coupling between said pri-' mary and secondary andprocuring the requisite amount of inductance for each of a plurality ofoscillation frequencies, means for independently varying the connectionsto said inductance, but normally in'unlocked amount of such section tocom relation therewith, and means for locking said last mentioned meansto said connections.

5. Thecombination with an antenna, of a winding of an oscillationtransformer, an inductance in circuit therewith, switches for changingthe amount of said inductance and said transformer winding in circuit,means causing all of said switches to move iniumson and means forpreventingdissipation of energy in that part of said inductance which isnot included in circuit.

6. The combination with an antenna, of s said capacities, movablecontacts adapted to co-operate with said stationary contacts,

and means mechanically connected with said movable contacts for changinthe relation of said capacities in circuit a ter'predetermined variationof said winding.

8. The combination with an antenna, of a plurality of inductancesections, a variable connection to each section for varying the amountof such section to compensate for antenna variations, switchingmechanism connecting to said variable'connections for determining thenumber of sections in circuit, means controlling the variableconnections but normall disconnected therefrom, and means controlled bythe switching mechanism for operatively connecting said last mentionedmeans to said variable connections.

9. A radio system comprising the combination with an oscillationcircuit, of a. plurality of inductance sections, avariable conthe nsatefor circuit variations, switching mec anism conmeeting to said variableconnections for determining the number of sections in circuit, means forindependently varying the connections to said inductance, but normallyin unlocked relation therewith, and means for locking said lastmentioned means to said connections.

10. A radio system comprisin the comnection to each section for varyingbination with an oscillation circuit, of a plurality of inductancesections, a variable.con-

nection to each section for varying the' amount of such section incircuit to compensate for circuit variations, switching mechanism forthrowing'in circuit said coniso nections in succession for determiningthe number of sections in circuit, means controlling the position of thevariable connections but normally out of operative relation therewith,and means controlled b said switching mechanism for placin said lastmentioned means in operative re ation with the connection which is thenin circuit.

11. The combination with an antenna, of a primary and secondary of anoscillation transformer and their circuits, additional inductance in oneof said circuits, switching mechanism including switches and connectionswith said primary, seconds. and said inductance for maintaining a preetermlned coupling between said primary and secondary for each of aplurality of oscillation fre uencies, variable contact elements for saidependentl varying said contact elements, and norma ly in unlockedrelation therewith,

vand means controlled by said switching mining the number of sections incircuit and for simultaneously changing said condensers from parallel toseries relation in said circuit, and v1ce versa.-

inductance connections, means for in 14. A radio system comprising atuning circuit, inductance therein having a plurality of sections,capacity, a movable switch element connecting to said sections and saidcapacity for determining by its movement the amount of each in circuit,and means carried 'by said switch element for varying the am unt ofcapacity without movement of said movable switch element.

15. The combination with the primary and secondary windings of anoscillation transformer and their current aths, of additional inductancein one of saici current paths and capacity in the other of said currentpaths, separate means for each of said inductance, said primary winding,and said secondary winding, for determining the amount of each incircuit, means actuating all of said means in unison, and meansco-operating with said last mentioned means for changing said capacityafter predetermined variation of the winding in circuit therewithi 16.The combination with variable rimary and secondary windings of anoscillation transformer and their current paths, of variable capacity inone of said paths, a

variable tuning element in the other of said paths, a switch for each ofsaid windings and for saidtuning element for determining the amount ofeach in circuit, means for actuating said switches in unison, and meanscontrolled by said last mentioned means for changing the amount ofeifective capacity after a predetermined variation of the transformerwinding in circuit therewith.

In testimony whereof we have hereunto afiixed our signatures.

GUY HILL. GEORGE H. CLARK.

